1. Field of the Invention
This invention relates to a belt clamping apparatus for a seat belt system comprising a belt retractor and a device which is controlled by at least one acceleration sensor and serves to lock gears which are connected to the reel shaft of the belt retractor, which clamping apparatus comprises a clamping wedge, which is guided on a sliding surface that is fixed to a housing to move parallel to a back-pressure plate which is guided is fixed to the housing and together with the clamping wedge defines a gap for the passage of the belt, and an actuating member, which is movable by the locking device and displaces the clamping wedge to its clamping position.
2. Description of the Prior Art
Such a belt clamping apparatus is known from U.S. Pat. No. 4,241,886 and comprises a blocking lever, which is pivoted on a pin to an inertial disk and in case of a response of a vehicle- or belt-sensitive acceleration sensor will interlock with an internal gear of a coupling disk so that a cam which is fixed to the reel shaft tends to rotate the coupling disk by means of a blocking lever as the belt is extracted. The rotation of the coupling disk causes claws to be extended to interlock with and block the teeth of the gears of the reel. Rotation of the coupling disk will also result in the raising of the control lever which consists of a link is raised so that the clamping wedge which is guided in oblique guides is moved against the belt and the latter is thus clamped between the clamping wedge and the back-pressure plate. In the known belt clamping apparatus that end at which the link for displacing the clamping wedge is linked to the coupling disk is constrained to follow a circular path like a connecting rod so that it is not possible to move the clamping wedge at a velocity which is optimally adapted to the velocity at which the belt is being extracted.
Another disadvantage of the known apparatus resides in the fact that the clamping wedge is pivotally movable about the articulated joint connecting the wedge to the link and for this reason it must be biased by the belt so that the sliding surface of the clamping wedge will be held in engagement with the oblique sliding surface which is fixed to the housing. As a result, the belt will be moved along the clamping surface of the clamping wedge in frictional contact therewith as the belt is extracted in the usual manner without a blocking of the belt retractor.